Single-mode microwave popping device

ABSTRACT

The present invention relates to an apparatus for popping kernels, comprising a heating chamber configured to contain kernels, a microwave emitter configured to produce microwave energy within the heating chamber and heat the kernels, a single-mode resonant microwave applicator configured to generate a stable focused high intensity microwave region within the heating chamber, and an air blower configured to create airflow within the heating chamber sufficient to move the kernels within the heating chamber.

THE FIELD OF THE INVENTION

The present invention relates to novel devices and methods for poppingkernels of cereal grains and seeds, such as popcorn.

BACKGROUND

Popcorn is made from un-popped corn kernels by heating the kernels untilthey “pop.” Popcorn kernels have a hard, outer hull that is generallyimpervious to moisture, while inside the hull the kernel contains starchand proteins with a certain amount of moisture and oil. Heating thekernels turns the moisture inside the hull into a superheatedpressurized steam, which causes the starch to gelatinize and pressure tobuild up in the kernel until the hull ruptures. When the hull ruptures,the pressure quickly drops, allowing the steam to expand. The expandingsteam causes the gelatinized starch and proteins inside the kernel toexpand into an airy foam, which when cooled sets into the typicalpopcorn “flake” or “puff.”

Early methods for making popcorn involved heating kernels in a basketover an open fire or flame, producing hot, dry, unevenly cooked popcorn.Other methods used oils and fats to aid in heating the kernels, such asin pan frying and frying machines, such as those developed by CharlesCretors in 1885. Later-developed appliances use hot air to heat thekernels and blow the popped kernels out a chute. More recently, standardmicrowave appliances are used to heat popcorn kernels in a bagcontaining the kernels and grease or fat.

The above methods have various disadvantages. One common disadvantage toall, however, is that they take too much time to produce suitablequantities of popcorn on demand which results in limited availability,and require advance preparation of large quantities of popcorn whichresults in product that may not remain fresh. The methods usedpreviously also result in non-uniform heating of the popcorn kernels,resulting in uneven or incomplete popping or kernels and a portion ofthe hard shell of many kernels remaining un-popped. Although standardmulti-mode kitchen microwave devices have been used in the art forpopping popcorn, the long processing times also often result in burningof a significant number of popcorn kernels and popcorn flakes, whichalso affects the taste and aroma characteristics of popped flakes in thesame container as the burned kernels and burned flakes. The aboveconsiderations add to the processing time, costs of production, loss inefficiency, and quality of end product.

Yet another disadvantage of most method of making popcorn is that arelatively large percentage of the kernels never pop. This results indecreased yield and often results in a person occasionally biting downon an un-popped kernel. Moreover, many consumers of popcorninadvertently heat popcorn kernels too long, which result in burnedpopped flakes having toxic levels of heterocyclic amines (HCAs) andpolycyclic aromatice hydrocarbons (PANs) that are potentiallycarcinogenic. For example, the Ohmy News International Science andTechnology website recently published a list of the top 10 carcinogenicfoods, with burned popcorn at the top of the list(http://english.ohmynews.com/articleview/article_view.asp?at_code=436169).In addition, recent reports suggest that chemicals present in manymicrowave popcorn products (to impart flavorings, such as butterflavor), as well as chemicals released from the packaging of microwavepopcorn bag itself, are also potentially toxic and carcinogenic.

Improvements in the prior art methods have been subject to certainconstraints. The prior art specifically teaches that popping results aresensitive to the rate at which the kernels are heated. For example, theWikipedia webpage for “Popcorn” teaches that if heated too quickly, thesteam in the outer layers of the kernel can reach high pressures andrupture the hull before the starch in the center of the kernel can fullygelatinize, leading to partially popped kernels with hard centers, and,if heated too slowly, leads to entirely un-popped kernels. Because akernel is not entirely moisture-proof, moisture can leak out of the tipwhen it is heated slowly, keeping the pressure from rising sufficientlyto break the hull and cause the kernel to pop.

The various aspects and embodiments of the present invention, asdescribed below, represent novel improvements on the above devices andmethods of the prior art. In addition, the methods and devices of thepresent invention produce novel popcorn flakes having unexpected andsurprisingly lower density and higher popping efficiency (more completepopping with less residual shell remaining).

SUMMARY OF THE INVENTION

The present invention relates to improved systems and devices forproducing popped cereal grains and seeds rapidly to provide variousimprovements over conventional production systems and methods. Variousaspects of the invention can be used to produce popped cereal grain andseed flakes more rapidly, having a greater yield in popped kernelsand/or having a greater yield in volume, surprisingly without burningthe flakes, despite the significantly higher intensity of microwaveenergy used.

In one aspect, the present invention relates to a microwave device forpopping kernels. In one embodiment, the microwave device comprises aheating chamber for containing kernels; a microwave emitter configuredto produce microwave energy within the heating chamber; a microwaveenergy focusing device configured to generate focused microwave energywithin the heating chamber and creating a stable microwave highintensity microwave region in the heating chamber; and an air blower forcausing movement of the kernels within the heating chamber and causingthe kernels to move within the heating chamber. In one configuration,the air blower is configured to move kernels in the heating chamber at asufficient speed to substantially uniformly heat the kernels. In anotherconfiguration, the air blower is configured to circulate kernels withinthe heating chamber at a velocity greater than 1 revolution per second.The air blower may be any type of air blower, for example, an axial orpropeller fan, a centrifugal or radial fan, a turbine, an aircompressor, cross-flow fans, combinations of such air blowers, and thelike. The moving kernels are subjected to focused microwave energywithin the heating chamber, sufficient to more uniformly heat thekernels and cause the kernels to pop.

In another aspect, there is provided an apparatus for popping kernels,comprising: a heating chamber for containing kernels; a microwaveemitter configured to produce microwave energy within the heatingchamber and heat the kernels; and at least one air blower disposed incommunication with the heating chamber for moving kernels within theheating chamber. In one configuration, the apparatus comprises awaveguide for channeling microwave energy into the heating chamber. Inanother configuration, the heating chamber is within the waveguide. Inyet another configuration, the heating chamber is smaller than themicrowave wavelength.

In another aspect, there is provided an apparatus for popping kernels,comprising: a heating chamber configured to contain kernels; a microwaveemitter configured to produce microwave energy within the heatingchamber and heat the kernels; a single-mode resonant microwaveapplicator configured to generate a stable focused high intensitymicrowave region within the heating chamber; and an air blowerconfigured to create airflow within the heating chamber sufficient tomove the kernels within the heating chamber.

In another configuration, there is provided an apparatus for poppingkernels, comprising: a heating chamber for containing kernels; amicrowave emitter configured to produce microwave energy within theheating chamber and heat the kernels; a single-mode resonant microwaveapplicator configured to generate a standing microwave energy fieldcomprising an array of one or more high intensity microwave regions; anda device configured to move kernels within the high intensity microwaveregions.

In another configuration, the present invention also provides a popcornvending machine, comprising: a kernel holding chamber configured tostore and dispense kernels; a heating chamber comprising an inletconfigured to receive kernels from the kernel holding chamber; amicrowave emitter configured to produce microwave energy within theheating chamber and heat the kernels; a single-mode resonant microwaveapplicator configured to generate a stable focused high intensitymicrowave region within the heating chamber; at least one air blowerdisposed in communication with the heating chamber, wherein the airblower is configured to blow air into the heating chamber, therebymoving kernels within the heating chamber and selectively removingpopped flakes from the high intensity microwave region when popped; anda heating chamber outlet connected to the heating chamber for receivingpopped flakes from the heating chamber and dispensing the popped flakesinto a container. In another configuration, the vending machinecomprises a dispensing tube connected to the heating chamber outlet,wherein the dispensing tube comprises a ribbed inner surface configuredto cause popped flakes to move spirally within the dispensing tube. Inanother configuration, the ribbed inner surface comprises a helicalcoil. In another configuration, the ribbed inner surface comprises aplurality of individual rings.

In a vending machine embodiment, the apparatus may also comprise anoutlet channel connected to an upper portion of the heating chamber fordischarging popped flakes. In another aspect, the vending machine mayalso comprise a heater for heating the airflow to be passed through theheating chamber. In another configuration, the machine may comprise acontrol module for controlling the temperature, flow rate, and flow pathof the air. In another configuration the machine may comprise a meteringsystem for delivering a specified quantity of kernels to the heatingchamber. In another configuration, the machine may comprise a system foradding flavoring to popped flakes. In another configuration, the machineis adapted to be activated by a purchase transaction. In anotherconfiguration, the purchase transaction comprises payment by any one ormore of a coin, paper bill, plastic charge card, or token. In anotherconfiguration, the purchase transaction comprises electronic payment.

In one configuration, the high intensity microwave region includes amicrowave energy maxima located within the heating chamber. In anotherconfiguration, a single high intensity microwave region is locatedwithin the heating chamber. In another configuration, a plurality ofhigh intensity microwave regions are located within the heating chamber.In yet another configuration, the high intensity microwave regionexcludes a microwave energy maxima located within the heating chamber.In another configuration, a plurality of high intensity microwaveregions are located within the heating chamber. In yet anotherconfiguration, the high intensity microwave region includes a microwaveenergy maxima located within the heating chamber. In anotherconfiguration, a single high intensity microwave region is locatedwithin the heating chamber. In another configuration, a plurality ofhigh intensity microwave regions are located within the heating chamber.In another configuration, the heating chamber has a diameter which isgreater than the microwave wavelength. In yet another configuration, thediameter of the heating chamber is such that kernels circulating withinthe heating chamber pass through a microwave energy maxima of twoadjacent high intensity microwave regions. In another configuration, theheating chamber encompasses a perimeter of two adjacent high intensitymicrowave regions that excludes a microwave energy maxima.

In one aspect, the device is configured such that the heating chamber isbetween two adjacent microwave energy minima nodes. In variousconfigurations, a sidewall of the heating chamber is positioned suchthat kernels at a heating chamber sidewall pass through a portion of thehigh intensity microwave region wherein the energy intensity is at least50% of the energy maxima, the energy intensity is at least 60% of theenergy maxima, the energy intensity is at least 70% of the energymaxima, the energy intensity is at least 80% of the energy maxima, theenergy intensity is at least 90% of the energy maxima, or the energyintensity is 100% of the energy maxima. In another configuration, thediameter of the heating chamber is approximately equal to one-halfwavelength and the heating chamber is positioned such that kernels at aheating chamber sidewall pass through two adjacent high intensitymicrowave regions. In another configuration, the diameter of the heatingchamber is approximately equal to one-half wavelength and the heatingchamber is positioned such that kernels at a heating chamber sidewallpass approximately through the energy maxima of two adjacent highintensity microwave regions. In another configuration, the apparatuscomprises a plurality of anti-node high intensity microwave regions. Inanother configuration, the heating chamber encompasses a plurality ofhigh intensity microwave regions and wherein the blower is configured torapidly move the kernels through the high intensity microwave regions.In another configuration, the apparatus comprises a plurality of heatingchambers, wherein substantially all of each of the one or more highintensity microwave regions is located within one of the plurality ofheating chambers. In another configuration, the single-mode resonantmicrowave applicator is configured to generate microwave intensitywithin the heating chamber to subject the kernels to microwave energysufficient to pop one or more of the kernels within approximately 10seconds. In another configuration, the device comprises two or moremicrowave energy sources such that the two or more microwave energysources constructively interfere at approximately the same locationwithin the heating chamber.

In accordance with one aspect of the invention, the apparatus comprisesan airflow input and an airflow outlet and the air blower causes airflowto pass in the airflow input, through the heating chamber, and out ofthe airflow outlet. In another aspect, the air blower is configured tocause airflow within the heating chamber in a horizontal directionsufficient to move kernels in a generally horizontal and generallycircular path in the heating chamber. In another aspect, the apparatuscomprises an air input in the side of the heating chamber, wherein thehorizontal airflow comprises airflow input into the heating chamber fromthe side of the heating chamber at an angle generally tangential to theheating chamber. In another aspect, the air blower may be one or moreblowers for creating an airflow pattern within the heating chamber tothereby move the kernels. In one configuration, the heating chamber isgenerally cylindrical in shape and the air blower is configured to causeairflow within the heating chamber in an approximately circular path andmove the kernels horizontally within the heating chamber in anapproximately circular path. In another configuration, the air blower isconfigured to cause airflow within the heating chamber in a verticaldirection, from a lower portion of the heating chamber upwardly to anupper portion of the heating chamber. This may include an airflow whichstarts generally horizontally to cause the kernels to move in agenerally circular direction within the heating chamber. The airflow mayalso be configured to form a helical movement path so that it causes thekernels to move generally circularly within the heating chamber and thenmoves upwardly in a helical or spiral configuration to carry poppedflakes out of the heating chamber. In the alternative, two air flowpaths could be used with one being more vertical. In anotherconfiguration, the air blower is configured to cause the verticalairflow at a rate sufficient to selectively move popped flakes out ofthe heating chamber when popped as a result of the increased drag of thepopped flakes. In another configuration, the air blower is configured tocreate airflow in both a vertical direction and a horizontal direction.

In another aspect of the invention, airflow may be directed from twodifferent sources to create a desired movement pattern for kernels priorto and after popping. One pattern may be configuration to providesubstantially circular airflow of the kernels prior to popping while theother may be configured to lift popped flakes from the heating chamber.Alternatively, a single airflow source may be provided to perform bothfunctions.

In accordance with another aspect of the invention, the kernels may bemoved within the high intensity microwave region by means of a rotatingheating chamber, such as a spinning cup, which causes the kernels tocirculate with the heating chamber while they are subjected to microwaveenergy. In one configuration, the spinning cup has sides that areoutwardly sloping. In another configuration, the spinning cup has aninternal flange forming a lip, wherein the lip prevents unpopped kernelsfrom escaping the spinning cup, but allows a popped flake to escape thespinning cup. In yet another configuration, the heating chambercomprises a spinning cup that is configured to move kernels within thehigh intensity microwave regions.

In accordance with one aspect of the invention, a heating element may beused to heat air passing into the heating chamber. The air being blowninto the airflow chamber may, for example, between ambient roomtemperature of 20° C. to 232° C., or alternatively from about 70° C. toabout 180° C., or alternatively from about 80° C. to about 95° C.

In accordance with yet another aspect of the invention, a heat sourcefor preheating the one or more kernels prior to being disposed withinthe heating chamber may be used. The heat source may be, for example,one or more of a flame, infrared heat and convection heat.

In another aspect, the present invention involves a heating chamber forcontaining kernels and a single-mode resonant microwave applicator forgenerating a standing microwave energy field comprising an array of oneor more anti-node high intensity microwave regions. The kernels aresubjected to the microwave energy in the one or more high intensitymicrowave regions, sufficient for the kernels to achieve a substantiallyuniform distribution of heat to cause the kernels to pop.

In accordance with another aspect of the invention, a microwave deviceis provided for popping cereal grain and seed kernels includes amicrowave energy source; a single-mode resonant waveguide applicatorwherein the waveguide is configured to focus microwave energy from themicrowave energy source at one or more regions within the waveguide; aheating chamber for heating kernels, and an outlet in communication withthe heating chamber for discharging popped flakes; and at least one airsource for circulating air within the lower portion of the heatingchamber and for passing air from the lower portion of the heatingchamber to the upper portion of the heating chamber.

In accordance with another aspect of the invention, the improved systemand method of making popped flakes heats kernels with microwaveelectromagnetic radiation by creating high intensity microwave regionswithin a heating chamber. The kernels are heated in the high intensitymicrowave regions until they pop into flakes. During the process,airflow passes through the heating chamber from a lower portion of thechamber to an upper portion of the chamber. The airflow blows the poppedflakes out of the heating chamber as a result of the increased dragcoefficient of the larger irregularly shaped popped popcorn, whileallowing the smaller more uniformly shaped un-popped kernels to remainin the chamber until they eventually pop.

In one aspect, the present invention also contemplates novel methods formaking popped cereals. In another aspect, the present inventioncomprises a method of popping kernels, comprising moving kernels withina heating chamber with airflow; and subjecting the kernels to focusedmicrowave energy sufficient to cause the kernels to pop, resulting inpopped flakes. In yet another aspect, the present invention comprises amethod for popping kernels, comprising generating a standing microwaveenergy field in a single-mode resonant microwave applicator, wherein thestanding microwave energy field comprises an array of one or more highintensity microwave regions; and subjecting kernels to the microwaveenergy in the one or more high intensity microwave regions, sufficientto cause the kernels to pop and produce popped flakes.

In one embodiment, a method is provided that comprises the steps ofpassing electromagnetic microwave radiation through a heating chamberand maintaining at least one anti-node of at least one microwave at afixed location within the heating chamber. The kernels are heated withthe microwave radiation at approximately the location of the one or moreanti-node.

In another aspect, the present invention provides a method of poppingkernels, comprising moving kernels within a heating chamber withairflow; and subjecting the kernels to microwave energy sufficient tocause the kernels to pop, resulting in popped flakes. In one embodiment,the microwave energy is focused microwave energy.

In yet another aspect, the present invention provides a method forpopping kernels, comprising generating in a single-mode resonantmicrowave applicator a standing microwave energy field comprising anarray of one or more anti-node high intensity microwave regions, andsubjecting kernels to the microwave energy in the one or more highintensity microwave regions, sufficient for the kernels to achieve asubstantially uniform distribution of microwave energy heat to cause thekernels to pop.

In yet another aspect, the present invention provides a method forpopping cereal grain and seed kernels, comprising generating in asingle-mode resonant microwave applicator a standing microwave energyfield comprising an array of one or more high intensity microwaveregions; providing a heating chamber encompassing the one or more highintensity microwave regions; delivering kernels to the heating chamber,wherein the kernels are moved through the microwave high intensitymicrowave region within the heating chamber to achieve a highly uniformdistribution of microwave energy heat until popped; and selectivelydischarging popped flakes from the heating chamber by upward airflow.

In one aspect, the present invention includes the heating chamber beingsmaller than the wavelength of the microwave energy being passed throughthe heating chamber, such that the kernels can circulate around andthrough the high intensity microwave region located within the heatingchamber. In one particular embodiment, the diameter of the heatingchamber is between about 1.75 inches (4.45 cm) and about 3 inches (7.62cm). In another embodiment, the diameter of the heating chamber isbetween about 2 inches (5.08 cm) and about 2.5 inches (6.35 cm). Thesmall diameter of the heating chamber subjects the popcorn to a highdose of microwave energy, causing it to pop rapidly. Movement of thepopcorn within the heating chamber makes the popcorn kernel heat evenly,allowing the starch in the center to gelatinize prior to rupture of thehull. Thus, the present invention allows for rapid popping withoutdrawbacks identified in the art.

In another aspect, the single-mode resonant microwave applicatorgenerates a standing microwave pattern comprising an electric fielddistribution of n half-wavelengths, where n is an integer. This mayinclude where n is greater than 1.

In one aspect, the present invention may include a plurality of heatingchambers. The microwave energy may be channeled such that each heatingchamber as a high intensity microwave region disposed therein and sothat the corn moves within the high intensity microwave region.

In one aspect, the single-mode resonant microwave applicator may beconfigured to generate microwave energy at a frequency from betweenapproximately 800 MHz and 30 GHz. In some aspects, the microwavefrequency is from between approximately 1 GHz to 5 GHz. In more typicalapplications, the microwave frequency is from between approximately 2GHz to 3 GHz. Many commercial microwaves use microwave frequency atabout 2.54 GHz.

In accordance with one aspect of the present invention a single-moderesonant microwave applicator may be configured to generate microwaveintensity within the heating chamber to subject the popcorn kernels tomicrowave energy sufficient to pop one or more of the popcorn kernelswithin approximately 10 seconds. An entire load of kernels may be poppedin less than 30 seconds, or even in less than 20 seconds.

In one aspect, the present invention may include a device with two ormore microwave energy sources such that the two or more microwave energysources constructively interfere at approximately the same locationwithin the heating chamber.

In another aspect, the present invention may include a device forcontinuously feeding kernels into the heating chamber.

In another aspect, the present invention provides novel popcorn flakeshaving significantly lower density, and improved popping efficiency.

The present invention further provides popcorn flakes having an averagevolume equal to or greater than about 900 mL per 100 flakes, 903 mL per100 flakes, 908 mL per 100 flakes, 912 mL per 100 flakes, 917 mL per 100flakes, or 928 mL per 100 flakes. In another aspect the inventionprovides popcorn flakes having a volume equal to or greater than about833 mL per 100 flakes, 917 mL per 100 flakes, 958 mL per 100 flakes, or1000 mL per 100 flakes.

In another aspect, the present invention provides a method of poppingkernels, comprising moving kernels within a heating chamber withairflow; and subjecting the kernels to focused microwave energysufficient to cause the kernels to pop, resulting in popped flakes,wherein the method produces popped flakes with an average popping yieldgreater than 94%, greater than 95%, greater than 96%, greater than 97%,or greater than 98%. In yet another aspect, the invention provides amethod for popping kernels, comprising: generating in a single-moderesonant microwave applicator a standing microwave energy fieldcomprising an array of one or more anti-node high intensity microwaveregions; subjecting kernels to the microwave energy in the one or morehigh intensity microwave regions, sufficient for the kernels to achievea uniform distribution of microwave energy heat to cause the kernels topop, wherein the method produces popped flakes with an average poppingyield greater than 94%, greater than 95%, greater than 96%, greater than97%, or greater than 98%

These and other aspects of the present invention are realized as shownand described in the following figures and related description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention are shown and described inreference to the numbered drawings wherein:

FIG. 1A shows a side view of an apparatus for popping popcorn inaccordance with the principles of the present invention;

FIG. 1B shows a top view of the apparatus of FIG. 1A;

FIG. 1C shows a perspective view of the apparatus of FIG. 1A;

FIG. 1D shows a view of an air blower and the heating chamber having twoseparate air inputs into the heating chamber from a single blower;

FIG. 1E shows a view of an air blower and heating chamber having twoseparate blowers, each having a separate input into the heating chamber;

FIG. 2 is a diagram of a microwave energy pattern and a heating chamberencompassing a single high intensity microwave region;

FIG. 3 shows a diagram of a microwave energy pattern and a heatingchamber encompassing two high intensity microwave regions;

FIG. 4 shows a diagram of a microwave energy pattern with a plurality ofheating chambers, each positioned within a high intensity microwaveregion;

FIG. 5 shows a side view of a heating chamber in the form of a spinningcup for moving kernels within a high intensity microwave region;

FIG. 6 shows an alternative single-mode microwave circular waveguideapplicator for popping kernels.

FIG. 7 shows a single-mode microwave device having a customer interface.

It will be appreciated that the drawings are illustrative and notlimiting of the scope of the invention which is defined by the appendedclaims. The embodiments shown accomplish various aspects and objects ofthe invention. It is appreciated that it is not possible to clearly showeach element and aspect of the invention in a single figure, and assuch, multiple figures are presented to separately illustrate thevarious details of the invention in greater clarity. Similarly, notevery embodiment need accomplish all advantages of the presentinvention.

DETAILED DESCRIPTION

The invention and accompanying drawings will now be discussed inreference to the numerals provided therein so as to enable one skilledin the art to practice the present invention. The drawings anddescriptions are exemplary of various aspects of the invention and arenot intended to narrow the scope of the appended claims.

There is thus disclosed improved systems, devices and methods for makingpopcorn flakes. Moreover, it will be understood that references in thefollowing disclosure to systems and devices are also applicable tomethods, which utilize related structures for the processes recited.Similarly, references to methods are also applicable of systems anddevices, which perform the processes in the operation of the reciteddevices. It will be appreciated that numerous changes may be made to thepresent invention without departing from the scope of the claims.

As used herein, the following terms have the meaning set forth below:

The term “kernel” means any one or more of several varieties of cerealgrain or seed having a sufficiently hard moisture-sealed exterior hulland dense starchy interior that it is capable of being popped or puffedto form irregularly shaped flakes when heated. Suitable cereal grainsand seeds capable of being popped include, for example, corn (popcorn),amaranth, sorghum, quinoa and millet. Although the specification hereinrefers frequently to “popcorn” cereals, as exemplary grain/see kernels,it is understood that the various apparatus, device and methodembodiments described herein may be used for popping cereals grains andseeds other than popcorn and that the scope of the claims referring to a“kernel” or “kernels” encompasses all such varieties of cerealgrains/seeds capable of being popped, and shall not be limited by anyparticular references in the specification to “popcorn.”

The term “flake” means a kernel that has been heated and popped.Similarly, the term “popped” refers to a kernel that has been heatedsufficient to cause the cereal grain or seed to puff into a flake.

The term “focused microwave energy” means microwave energy that has beendirected or focused into a defined area, resulting in a substantiallystable and homogeneous field pattern surrounding the load being subjectto the microwaves. Focused microwave energy may be generated, forexample, by reflecting microwaves in a multi-mode microwave applicatorhaving multiple resonant modes of microwave energy propagation, or bygenerating a standing wave pattern in a single resonant mode (i.e.,single-mode) microwave applicator, where the standing microwave patterngenerates microwaves that constructively interfere to generate stableareas of high intensity microwave energy.

The term “high intensity microwave region” means a region of focusedmicrowave energy in a microwave applicator, wherein the microwaves areof sufficiently high intensity to cause rapid heating and popping ofcereal grains and seeds. A high intensity microwave region typicallyincludes the location of maximum energy intensity. Although a highintensity microwave region may encompass the location of energy maxima,it does not necessarily include the point of energy maxima. Because, ina single-mode resonant microwave applicator, the energy intensity variessinusoidally from the energy minimum (the node, where electro-magneticwaves destructively interfere) and the energy maximum (the anti-node,where the electro-magnetic waves constructively interfere), a highintensity microwave region may also encompass the region of energyintensity that is less than the energy maximum while excluding theactual location of energy maximum. A heating chamber may encompass twohigh intensity microwave regions, without encompassing the points ofenergy maxima, where the perimeter of the heating chamber (i.e., thesidewalls) passes through the region between the two energy maximawithout actually passing through the energy maxima. Accordingly, a “highintensity microwave region” shall be construed to comprise thoselocations having a microwave energy greater than the microwave energyminima and having a stable well-defined microwave energy maxima.

The term “single-mode,” as used in reference to microwave applicatorsherein, means that the superposition of incident and reflect waves in aresonant cavity results in a standing wave pattern with a singleresonant mode of microwave energy, thereby generating high intensitymicrowave regions containing energy maxima that are stable atwell-defined and predictable positions within the applicator. Incontrast, traditional multi-mode microwave applicators propagatemicrowaves with multiple modes of energy, each with varying intensityand at irregularly spaced intervals. A single-mode resonant microwaveapplicators establish significantly higher electric field strengthscompared to a traveling wave or a multi-mode applicator, and aregenerally more compact, as the dimensions of the resonant cavities are afunction of the wavelength typically used for microwave heating (2.45GHz) of food articles. The particular size and dimensions of asingle-mode microwave applicator can be determined by those skilled inthe art of microwave heating, by utilizing Maxwell equations, whichcontain all the necessary parameters needed to define the standing wavepattern desired to be established in a particular case, including thegeometry and dimensions of a resonant waveguide applicator operating insingle-mode.

The term “popping yield” means the percentage of popcorn kernels thatare popped, as determined by popping at least 8 batches of popcornkernels with 60 kernels in each batch, to produce popcorn flakes,calculating the percentage of kernels in each batch that produce poppedpopcorn flakes, and averaging the percentage of kernels in the 8 batchesthat produce popped popcorn flakes.

The term “volume,” as used herein in reference to the volume or averagevolume of popped flakes, means the volume of a quantity of flakes, asdetermined by popping at least 8 batches of kernels, with 60 kernels ineach batch, to produce popped flakes, placing the popped flakes in a1000 mL graduated cylinder, placing the cylinder on a cushioned surfaceand tapping the top of the cylinder lightly by hand 6 times andmeasuring the volume (repeating as many times as necessary until anychanges in volume are not statistically significant), and thendetermining the final volume. The average volume is calculated byaveraging the final volume of at least 8 batches.

It is further understood that use of definite articles such as “the” or“a” shall be construed to include one or more elements and shall not beconstrued to be limited to a single element. Elements shall be limitedto single elements only if expressly modified by a term such as“single,” “one,” “sole,” “only,” or the like.

The present invention generally relates to novel devices and methods forpopping cereal grain and seed kernels which may achieve a variety ofdesired outcomes, such as increased popping speed, increased yield,reduced density, a change in general popcorn flake structure, and otheroutcomes discussed herein. The novel devices and method may utilizefocused microwave energy to create a high intensity microwave fielddensity that more uniformly heats kernels at a high rate to cause thekernels to achieve a critical heating temperature simultaneously andthereby pop more completely, with less residual popcorn shell remaining.Although the use of multi-mode microwave devices have been used in theart for popping kernels, the present invention relates to the discoverythat focused microwaves, such as single-mode microwave applicators, mayresult in improved popping efficiency of kernels, as well as improvedspeed of popping. In addition, the focused microwaves may result inimproved popped flakes having lower density, larger size, higher poppingefficiency and improved taste characteristics.

The devices and methods described herein confer significant advantagesover the prior art, including, for example, providing devices that aresignificantly smaller in size, which enables ease of storage andimproved portability, and consume significantly less energy. Forexample, such devices may be used to provide food for emergencyhumanitarian aid, disaster relief or military purposes, where there is aneed to produce high volumes of nutritional food, inexpensively, inremote locations where there may be no significant energyinfrastructure. The portability of the devices disclosed herein may alsobe a significant advantage where there is a demand for large quantitiesof popcorn at entertainment venues, as the devices enable high volumeoutput of fresh product, and avoid the need of advance production ofpopcorn that may not be fresh and that requires popping off-site andtransportation to the venue. As disclosed in more detail herein, thepopcorn flakes produced by the devices and methods disclosed herein arealso novel in that they have a higher volume (lower density), improvedpopping yield (resulting in more of the hard kernel being puffed into anedible product, with less residual shell), improved texture andmouth-feel, as well as improved molding ability (resulting from residualmoisture causing the popped flakes to have increased gumminess thatallows popped flakes to stick together better immediately followingpopping of the flakes).

While various embodiments implementing different aspects of the presentinvention are discussed below, it has been found in accordance with theprinciples of the present invention than multiple advances may beachieved in the popping of kernels. For example, in accordance withaspects of the invention it has been found that improvements in poppingkernels can be achieved by placing kernels in a heating chamber disposedwithin a within a single high intensity microwave region, i.e. thechamber closely surrounds or encompasses the area of peak energy of astanding microwave signal. As the kernels move within the high intensitymicrowave region, the kernels are able to heat rapidly, thereby causingthe kernels to heat and rupture in a much shorter period of time thanconventional oil, air and microwave popping systems currently available.Additionally, all of the kernels are subject to a substantially equalamount of heat, and the heating within each kernel may be generally moreuniform than conventional methods. This results in kernels popping morerapidly and may result in both a significantly higher yield in thenumber of kernels popped and in the average volume of the kernels whichhave popped.

As shown in the Example section below, tests were conducted to comparethe methods and systems of the present invention with methods known tothose in the art, including hot air popping and microwave bag popping.In this comparison, the methods and systems of the present inventionshowed significant improvements in popping time, popping efficiency (thepercentage of kernels that actually popped), and increased flake volumewhich results in improved texture and mouth feel.

Based on the above testing results, the present invention significantlyimproves popping time. Using a hot air popper (which is known in theart), popping with a load of 60 popcorn kernels started within 34-61seconds (on average 48 seconds) and was completed within 55-109 seconds(on average 78 seconds). Similarly, using a standard kitchen microwavebag, popping started within 65-73 seconds (on average 69 seconds) andwas completed popping within an average of 189 seconds. In contrast,using a high intensity microwave device, in accordance with the presentinvention, popping started and was completed within significantlyshorter periods—initial popping of 60 kernels started within as littleas about 9-12 seconds (on average within about 10 seconds), whilepopping was completed within 16-19 seconds (on average within about 17seconds). Thus, the methods and systems of the present invention providea significant improvement in the time it takes of initiate and finishpopping a batch of popcorn kernels, showing a reduction in the averagetime of over 78%.

Not only do the systems and methods of the present invention pop thekernels faster, it has been found that the yield is also significantlyhigher. For example, conventional systems for popping kernels (hot airand microwave bags) result in popping an average of 89-93% of allkernels (with individual batches ranging from 75-97%). The remainingkernels are ejected out of the popper either by the airflow, are carriedwith popped kernels as they are expelled, or simply remain unpoppedinside the microwave bag. The tests reported below showed that themethods and systems disclosed and claimed herein result in an averagepopping yield of 98%, with individual batches being as high as 98%, 99%and even 100% for some batches. Thus, the methods of systems of thepresent invention produce a significantly greater average yield.

In addition, the rapid heating and rupturing of the kernels inaccordance with the present invention resulted in popped flakes whichwere of larger volume than those popped by the conventional methods. Inthe tests described below, the volume of multiple batches of 60 poppedflakes, using conventional hot air and microwave bag methods and focusedmicrowave methods disclosed herein, were compared. These tests showedthat the methods of the present invention resulted in an averageincrease in volume of popped flakes of about 13% compared to kernelspopped in a microwave bag, and over 30% increase in volume compared tokernels popped with a hot air popper. Accordingly, the methods andsystems of the present invention provide significant improvements to thesize of popped flakes, which results in improved texture and mouth feelof the popped flake.

It has also been discovered that the use of high intensity microwaves inaccordance with the present invention result in a significant reductionin power consumption. For example, a typical hot air popper consumesover 26 W-hours of energy (1200 W for 78 seconds to cook 60 kernels) anda standard kitchen microwave consumes approximately 14 W-hours of energyfor a 3.5 oz bag of microwave popcorn (1500 W for 189 seconds for 342kernels, normalized for 60 kernels). In contrast, the use of a focusedmicrowave device in accordance with the present invention consumes only9 W hours of energy (2000 W for 17 seconds for 60 kernels). The methodsand devices of the present invention further result in significantreduction in energy consumption and cost savings, amounting toapproximately 35%.

Finally, the methods and devices of the present invention also result ina significant reduction or elimination of burned flakes. The poppedflakes made by the methods and devices of the present invention, whencompared to popped flakes made by methods and devices previously used(such as standard kitchen microwave devices), show significant reductionin burned, charred and darkly colored areas which could potentially betoxic or carcinogenic.

Systems and Devices

The basic configuration of the systems and devices of the presentinvention comprises a microwave emitter, such as a magnetron, connectedto a microwave antenna for emitting microwave energy into a heatingchamber. The systems and devices may include a waveguide cavity ormicrowave focusing device, such as a single-mode resonant cavity, withinwhich a heating chamber is located. The purpose of the microwave cavityand associated hardware is to maximize the electric field at the load(the kernels) and optimize the microwave coupling efficiency. Themicrowave applicators of the present invention may generate highintensity microwaves within the heating chamber to subject the kernelsto microwave energy sufficient to pop one or more of the kernels.

One embodiment of a system for making popped flakes in accordance withthe present invention is shown in FIGS. 1A-C. A kernel popping system,generally indicated at 10, may include a microwave energy emitter 14 forproducing microwave energy within a heating chamber 18. Appropriatemicrowave energy emitters 14 are known and may be selected according tovarious design considerations known to those skilled in the art anddetermined without undue experimentation. Microwave energy emitterstypically comprise a magnetron 22 for generating microwaves and amagnetron antenna 24 disposed within a waveguide 26. The waveguide 26directs microwave energy within a microwave cavity 28 defined by thewaveguide to the load (such as popcorn kernels, not shown) that isdisposed within the heating chamber 18.

The magnetron 22 may generate microwave energy at any frequency suitablefor heating grains or cereals having some water content. Generally,grains or cereals may be heated with microwaves at a frequency rangingfrom 1 MHz up to 30 GHz. The range of frequencies more commonly used isfrom about 400 MHz to about 20 GHz. The ISM bands commonly used forindustrial, scientific and medical uses (including heating/cooking foodproducts), as prescribed by certain government regulatory agencies,include 896 MHz, 915 MHz and 2.45 GHz. For example, in some embodiments,the magnetron is tuned to generate microwave energy at a frequency thatmaximizes the rapid oscillation of water molecules in the load beingheating, such as 2.45 GHz. As will be apparent to those skilled in theart, other operating frequencies may also be used effectively. Thepresent invention contemplates use of microwave energy at any frequencysuitable for popping kernels.

The selection of appropriate microwave generators is considered to bewithin the ordinary skill in the art. It is understood that typicalmicrowave generators utilize magnetron oscillators, which may includecontinuous wave generators to produce a relatively narrow outputfrequency spectrum for use with small loads, as in the case of smallbatch volumes of kernels.

Microwave Focusing Device

The present invention employs focused microwaves as a means of creatinghigh intensity microwave energy for rapid high-temperature popping ofcereal grains and seeds. Microwave energy may be focused, for example,by reflecting microwaves in a multi-mode applicator so as to create astable and homogeneous “high intensity microwave region” (defined below)at defined location, such as a small heating chamber suitable.Alternatively, microwave energy may be focused through use of adaptivemicrowave phased arrays to concentrate the microwave energy at apredetermined area. For example, suitable adaptively focused microwavesystems may be constructed having a phased array of multiple radiatingantenna elements for a tightly focused microwave beam having a maximumdimension on the order of 2-10 cm or larger, as described by Fenn A J,Adaptive Antennas and Phased Arrays for Radar and Communications,Norwood, Mass., Artech House Publishers, 133-160 (2008). Alternatively,microwave energy may be focused by use of a single-mode microwaveapplicator, which generates a stable standing wave pattern having one ormore “high intensity microwave region” of energy maxima. Othertechniques and devices for focusing microwaves are also contemplated tobe within the scope of the present invention.

In accordance with the present invention, one particular microwaveenergy focusing device is shown in FIG. 1A-1C. A microwave energyfocusing device of the present invention, may comprise a waveguide 26,which includes a microwave cavity 28 within which a heating chamber 18containing popcorn kernels is located. The microwave energy focusingdevice provides for high intensity focused microwave energy within theheating chamber and creates one or more stable evenly-spaced microwaveanti-node high intensity microwave regions in the heating chamber asshown and discussed in additional detail with respect to FIGS. 2, 3, 4,and 5. The length and shape of the waveguide 26 may be configured tocreate standing waves such that high intensity microwave energy regions(i.e., microwave energy maxima) are evenly spaced at fixed locations.These high energy regions are referred to herein as “high intensitymicrowave regions.”

The use of focused microwaves may be achieved by any one of severalapproaches. For example, in one embodiment, microwave energy may befocused by reflecting microwaves from a shaped surface that is highlyreflective of microwave energy, so that radiation emitted from themicrowave source is reflected towards the heating chamber containing thepopcorn kernels. Microwaves may be focused by reflecting off a surfacesuch as a parabolic dish, a horn antenna, a hemispherical dome, etc.Alternatively, microwaves may be focused by means of a microwave lens.

In other embodiments, the focused microwaves may be achieved by use of asingle-mode resonant microwave applicator. A single-mode resonantmicrowave applicator has the ability to create a standing wave pattern,which is generated by the interference of fields that have the sameamplitude but different oscillating directions. This interface generatesan array of nodes where microwave energy intensity approaches zero, andan array of antinodes where the magnitude of microwave energy is at amaximum. Single-mode resonant applicators are designed so that thedistance of the sample from the magnetron is such that the sample can beplaced at the antinodes of the standing electromagnetic wave pattern.Single-mode resonant applicators may be designed such that the standingelectromagnetic wave pattern generates an array of one or more anti-nodehigh intensity microwave regions where the magnitude of microwave energyis at a maximum. As shown in FIGS. 2, 3, and 4, these anti-nodes aregenerated at evenly spaced intervals (where there is a plurality) andare sufficiently stable and localized that a load can be accuratelyplaced within the anti-node high intensity microwave region withpredictable and repeatable results.

In some embodiments, the single-mode resonant microwave applicator mayinclude a shorted rectangular waveguide cavity 28 comprising a metaltube having a generally rectangular cross section and one or moreshort-circuit wall 29 a and 29 b at one or more end of the metal tube,as shown in FIG. 1A. It is contemplated that single-mode resonantmicrowave applicators may also be constructed of tubular or circularwaveguides. In another embodiment, the microwave focusing device may becircular self-tuning single-mode resonant cavity, as shown in FIG. 6(made by CEM Corporation, Matthews, N.C.). In a single-mode resonantmicrowave applicator, the superposition of the incident and reflectedwaves establish a standing wave pattern that is stable, well-defined inspace, has evenly and predictably spaced positions of energy maxima.These features enable a dielectric material, such as popcorn kernels, tobe placed in one or more localized positions of maximum energy orconcentrated electric field (referred to, herein, as a “high intensitymicrowave region”) for optimum transfer of the electromagnetic energy tothe dielectric material. In some embodiments, the single-mode resonantmicrowave applicator generates a standing microwave pattern comprisingan electric field distribution of n half-wavelengths, where n is aninteger. In some embodiments, n is greater than 1. In some embodiments,n=1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, or greater.

In some embodiments, the single-mode resonant microwave applicator maybe configured to generate a plurality of anti-node high intensitymicrowave regions. In some embodiments, as shown in FIG. 2, at least oneof the one or more high intensity microwave regions is located withinthe heating chamber. In other embodiments, the heating chamberencompasses a single high intensity microwave region. In otherembodiments, such as shown in FIGS. 3 and 4, the heating chamberencompasses a plurality of high intensity microwave regions. Forexample, as shown in FIG. 4, the device may comprise a plurality ofheating chambers, wherein each high intensity microwave region islocated within a single heating chamber. FIG. 3 shows an embodiment inwhich a single heating chamber spans two adjacent high intensitymicrowave regions.

In some embodiments, the device may include two or more microwave energysources such that the two or more microwave energy sourcesconstructively interfere at approximately the same location within theheating chamber.

Those skilled in the art understand that the choice of waveguide sizedepends on such considerations as operating frequency, power rating,component availability and cost. Various waveguide sizes commonly usedfor industrial microwave heating include 2450 MHz (S band) and 915 MHz(L band) include. For example, a WR284 (7.21 cm×3.40 cm) waveguide isoften the preferred choice for 2.45 GHz operation at average powerlevels of up to 6 kW. Waveguides may be made of such materials asaluminum, copper, or stainless steel.

The length of such waveguides may vary, depending on the number of highintensity microwave regions desired in the waveguide. Microwavewaveguide cavities may be designed to support any one of various TE₁₀rectangular waveguide resonant modes, including TE₁₀₁, TE₁₀₂, TE₁₀₃,TE₁₀₄, TE₁₀₅, etc., which generate 1, 2, 3, 4 and 5 high intensitymicrowave regions, respectively. Additional high intensity microwaveregions may be utilized advantageously in high volume manufacture ofpopcorn flakes. In accordance with certain embodiments of the invention,a heating chamber for popping popcorn kernels may encompass one or morehigh intensity microwave region within a single high intensity microwaveregion. In some embodiments, the heating chamber encompasses a singlehigh intensity microwave region. In other embodiments, the heatingchamber encompasses two high intensity microwave regions. In someembodiments, the entire waveguide comprises the heating chamber, andpopcorn kernels may pass through a plurality of high intensity microwaveregions as they cascade down the length of the waveguide. In yet otherembodiments, the devices of the present invention may include multipleoutlets corresponding to each of the one or more heating chambers. Thus,by using multiple heating chamber and multiple outlets, one maysignificantly increase the quantity of flakes produced.

It is also understood that the design of waveguides may requireappropriate isolators to allow microwave power to pass through in theforward but not reverse direction, so as to protect the microwavegenerator (i.e., the magnetron) from the damaging effects of reversepower. Alternatively, microwave devices may also include circulators,which do not absorb power and therefore require a separate “dummy”waveguide load connected to the circulator to absorb the reverse power.

The systems and devices of the present invention may also includeimpedance tuners, which couple microwave power to a load by matching therespective complex impedances between the load and the microwave powersource.

In some embodiments, the present invention contemplates achievingenhanced heating uniformity in a single-mode applicator by reciprocatinga standing wave inside the applicator. For example, the system may splitthe generate microwave power into two equal and coherent wave fronts.The two forward power wave fronts are then diverted through rotatingphase shifters and then reflected back through the phase shifters beforebeing routed to opposite ends of the applicator. The two coherent wavefronts converge inside the applicator to generate a pattern of standingwaves. The phase shifters operate by rotating a thin dielectric slabinside the waveguide with its rotational axis in the plane of theelectric field. When the slab, having low dielectric loss and highdielectric constant characteristics, rotates between positionsperpendicular to and parallel with the waveguide centerline the phaseshift alternates sinusoidally from near zero to maximum. Adjusting theslab geometry varies the phase shift amplitude. Rotating both phaseshifters synchronously and exactly 90 degrees out of phase with eachother will then cause a sinusoidal reciprocation of the standing wavepattern inside the applicator at constant amplitude.

In one particular embodiment, for example, the microwave cavity may be asingle-mode resonant cavity furnace, comprising a rectangular waveguidedesigned to support TE₁₀₃ rectangular waveguide mode, and is constructedfrom WR284 copper waveguide (7.21 cm×3.40 cm). The guide wavelength at2.45 GHz in WR-284 is λg=23.12 cm and the total length of the furnacecavity is approximately l=1.5λg=34.8 cm. A kernel loading inlet islocated at approximately 17.50 cm from the source end (near the half-waypoint from each end), where the heating chamber is located at a fieldmaximum (a high intensity microwave region) at resonance.

As will be appreciated, those skilled in the art may construct and useother single-mode resonant cavity furnaces having different dimensionsthat are suitable for popping popcorn kernels. Larger single-moderesonant cavity furnaces may be used, for example, to pop largerquantities of popcorn on a commercial or industrial scale.

In addition, the present invention further contemplates that highintensity focused microwaves may be generated at a predetermined andstable location with the use of microwave focusing devices, such asmicrowave reflectors and lenses. For example, microwave reflectors maybe used, having a parabolic or hemispherical shape, for focusingmicrowaves at a specific location.

Heating Chamber

As illustrated in the accompanying drawings, the system and devices ofthe invention may include a heating chamber 18 for containing thepopcorn kernels (not shown) while being heated. The heating chamber 18is configured to contain the popcorn kernels within a defined area thatencompasses one or more high intensity microwave region. In someembodiments, the microwave energy focusing device, such as waveguide 26,is configured such that at least a portion of one microwave energymaxima is located within the heating chamber 18. In some embodiments,the heating chamber 18 is constructed so as to permit or cause thekernels to move within or through one or more high intensity microwaveregion. In some embodiments, the heating chamber 18 encompasses a singlehigh intensity microwave region or a portion of a single high intensitymicrowave region. In other embodiments, the heating chamber mayencompass more than one high intensity microwave region, or a portion ofmore than one high intensity microwave region. In some embodiments, theheating chamber is constructed of a material that is generallytransparent to microwaves, such as Teflon, glass, plastic or ceramic, soas to allow the microwaves to pass through the heating chamber walls andheat popcorn kernels disposed within the heating chamber. The dimensionsof the heating chamber wall may also vary without significantly alteringthe microwave characteristics. By way of example, the heating chamberwall may, for example, be anywhere from 1-15 cm, or in come embodimentsfrom 2-10 cm, or in other embodiments from 3-5 cm. A suitable thicknesswould, for example, be approximately 4 cm.

In some embodiments, the devices of the present invention may comprise aplurality of high intensity microwave regions within a single microwaveapplicator. In such cases, the devices may also contain a plurality ofmultiple heating chambers within the microwave applicator. It is furtherunderstood that a single heating chamber may encompass more than onehigh intensity microwave region. The heating chamber need not beconcentric with a single high intensity microwave region. The heatingchamber may, for example, pass through the high intensity microwaveregion on one side of the heating chamber while the other side of theheating chamber is not located in a high intensity microwave region.Similarly, the heating chamber may pass through all or part of a highintensity microwave region on one side of the heating chamber, whilepassing through all or part of a high intensity microwave region on theother side of the heating chamber. In such cases, the popcorn kernelsmay achieve a sufficiently high level of high intensity microwaveheating as long as they are cycling through the heating chamber andthrough the separate high intensity microwave regions fast enough thatthe heating effect of the high intensity microwave region averages out.

In some embodiments, the heating chamber for heating popcorn kernels mayinclude a lower portion 30 and an upper portion 32. The lower portion 30may be disposed within the waveguide cavity 28 at the location offocused microwave energy within the waveguide. The heating chamber 18may also include an outlet 34 connected to an upper portion 6 of theheating chamber 18 for discharging popped popcorn.

In some embodiments, the heating chamber 18 may be connected to at leastone air source, such as an air blower 40, for circulating air within thelower portion 30 of the heating chamber 18 and/or for passing air fromthe lower portion 30 of the heating chamber 18 to the upper portion 32of the heating chamber 18 and out of the heating chamber 18 through theoutlet 34.

In some embodiments, the heating chamber 18 may be configured to allowpopcorn kernels to move within and the through one or more highintensity microwave region within the heating chamber. For example, thekernels may be moved through the high intensity microwave region byairflow within the heating chamber 18 generated by the air source 40,such as a blower 40.

In another embodiment, as shown in FIG. 5, the kernels may be movedthrough the high intensity microwave region by a rotating containerwithin which the kernels are disposed. In some embodiments, the kernelsmay be moved through the high intensity microwave region by acombination of airflow and a moving container. In some embodiments, therotating container 4 may also include an inwardly facing lip 50,sufficient to prevent un-popped popcorn kernels 90 from being removedfrom the container by airflow or by centrifugal force of the rotatingcontainer and simultaneously allow popped popcorn 94 to be removed fromthe container by airflow.

In some embodiments, as shown in FIG. 1, airflow is generated by anexternal air source 40, which then passes into the heating chamberthrough an air inlet 44, through the heating chamber 18, and finally outof the heating chamber through the outlet 34. The air inlet 44 may beconfigured with a grating, holes, or sieve with sufficiently small airinlet holes that un-popped kernels do not fall through the holes backinto the blower, but large enough to enable sufficient airflow to movethe kernels within the heating chamber.

The heating chamber 18 may be stationary, as shown in FIGS. 1 and 2,relying on airflow to move the corn kernels within or through the highintensity microwave regions. Alternatively, as shown in FIG. 5, theheating chamber 18 may rotate or move so as to cause the corn kernels tomove within or through the high intensity microwave regions. As shown inFIGS. 1 and 1A, the air source 40 may cause the kernels to travel in agenerally circular path in the heating chamber while the kernels areheated to cause more equal heating of the kernels. The same air source40 a or an alternate air source 40 b may also be used lift popped flakesout of the heating chamber 18. It will be appreciated that a flake has amuch greater volume for the given mass (which essentially remains thesame before and after popping, less any dissipated moisture afterpopping) and thus has increased drag compared to an un-popped kernel.The airflow through the heating chamber 18 may be configured to havesufficient velocity to carry a popcorn flake out of the heating chamber,but lack sufficient velocity to carry an un-popped kernel of the heatingchamber. This promotes popped popcorn flakes leaving the heating chamber18 after popping, while allowing the un-popped kernels to remainingwithin the heating chamber until they achieve a sufficient level of heatand rupture.

Heating Chamber/Container

The heating chamber 18 functions to circulate un-popped popcorn kernelswithin and through one or more high intensity microwave region of highintensity microwave energy, so as to achieve rapid and uniform heatingof the popcorn kernels. For example, the heating chamber 18 may comprisea container within which un-popped popcorn kernels are disposed. Thecontainer may be cylindrical in shape or conical or funnel(frustoconical) in shape. In some embodiments, the container may beadapted to include one or more air inlets 44 a, 44 b and an outlet 34.Airflow within and through the container may be utilized to move thepopcorn kernels and achieve a more even distribution of heating of thekernels as the movement within and through the one or more highintensity microwave regions results in a sufficiently high averageheating of the popcorn kernels.

In other embodiments, the container 18 may be configured to rotate so asto move the kernels within or through one or more high intensitymicrowave region, with or without airflow, thereby achieving an averagehigh intensity heating sufficient to cause rapid and uniform heating ofthe popcorn kernels. In some embodiments, the container 18 may beconfigured to rotate so as to move the kernels horizontally within orthrough one or more high intensity microwave region, while also beingconfigured to include an air inlet 44 and air outlet 34 for verticalairflow, so as to selectively remove popped kernels from the containerwith the upward vertical flow of air. The rotation of the heatingchamber 18 may also be used advantageously to hold popcorn kernelsagainst the side wall 38 of the heating chamber 18 by centrifugal forcecreated by rotation of the heating chamber 18, thereby increasing therequired force of airflow to remove the kernel before popping, andpermitting increased force of airflow to achieve selective removal ofpopped flakes from the container. Moreover, the rotation of thecontainer 18 further forces un-popped kernels to line up against theside wall, creating a trajectory of the kernels at a constant radiusthrough the one or more high intensity microwave region that iswell-defined, so as to achieve a more uniform average high intensityheating of the kernels.

The container may also be configured in the form of a cylinder or cone,with an inwardly facing lip 50 at the top sufficient to preventun-popped kernels from exiting the container when the container isrotating. While rotation of the container forces popcorn kernels to thetop by centrifugal force, the lip 50 (FIG. 5) prevents un-popped kernelsfrom exiting the container. Popcorn flakes, having a size larger thanthe size of the lip, pass over the lip 40 by such means as airflow orcentrifugal force and are removed from the container 18.

In another embodiment, the heating chamber 18 may be substantiallycylindrical in shape, with vertical side walls 38, with an inwardlyfacing lip 50 at the top of the container. In embodiments utilizingvertical airflow to remove popped kernels, the inwardly facing lip 50 issized so as to prevent un-popped kernels from exiting the container,while popped kernels, being sized larger than the extension of theinwardly facing lip, are blown over the lip by vertical airflow andremoved from the container.

Air Source

The heating chamber 18 may be connected to one or more air source 40,such as a fan or air blower, for creating airflow within the heatingchamber and causing the popcorn kernels to move within the heatingchamber 18. In some embodiments, the device comprises one or moreairflow inlets 44 and an airflow outlet 34. The blower causes airflow topass through the heating chamber 18. In some embodiments, the blower isconfigured to cause airflow within or through the heating chamber 18from a lower portion 30 of the heating chamber to an upper portion 32 ofthe heating chamber and through the airflow outlet 34 of the heatingchamber 18. The airflow outlet 34 of the heating chamber 18 is connectedto an outlet tube 60 that discharges the air and the popped popcornflakes into a receptacle 64.

The blower may be configured to cause airflow within the heating chamberin a horizontal direction so as to cause the un-popped kernels ofpopcorn to circulate within and through the microwave high intensitymicrowave region. As shown in FIGS. 1 and 1A, the heating chamber 18 mayfurther comprise an air input 44 a in the side wall 7 of the heatingchamber, wherein the horizontal of airflow comprises airflow inputtangentially into the heating chamber 18 from the side wall 38 of theheating chamber 18 at an angle generally perpendicular to the radius ofthe cylindrical heating chamber (see FIG. 1A). The blower or other airsource 40 may also be configured to cause airflow within the heatingchamber 18 in an approximately circular path and move the popcornkernels generally horizontally within the heating chamber in anapproximately circular path within and through the high intensitymicrowave region. In some embodiments, the heating chamber 18 iscylindrical and substantially circular in cross-sectional shape and theblower is configured to cause airflow within the heating chamber in anapproximately circular path and move the popcorn kernels horizontallywithin the heating chamber in an approximately circular path. In someembodiments, an air source 40 may also be provided to cause airflowwithin and through the heating chamber 18 in a vertical direction, so asto selectively lift popped popcorn flakes upwardly and out of theheating chamber 18. For example, the device may be configured with twoair blowers, air blower 40 a and a second air blower 40 b, as shown inFIG. 1E. The blower 40 b may be configured to cause vertical airflowfrom a lower portion 30 of the heating chamber 18 upwardly to an upperportion 32 of the heating chamber 18 and thereby selectively move thepopped popcorn out of the heating chamber when popped. Because un-poppedkernels are smaller and have a smooth surface they have less air dragthan popped flakes, which are larger and have an irregular surfacehaving greater air drag. The vertical airflow is selected so as to liftpopped flakes against the force of gravity out of the heating chamber18, while not lifting un-popped kernels out of the heating chamber.

In some embodiments, one or more air source 40 may be configured tocreate airflow in both a vertical and horizontal direction. For example,the blower may be configured to create airflow in an upwardly spiraldirection. Alternatively, the airflow may be configured to form a vortexwith the heating chamber 18 and/or outlet tube 60. Two separate airsources 40 may be utilized to provide vertical and horizontal airflow.The airflow may be generated, for example, by a first blower 40 a and asecond blower 40 b, wherein the first blower is configured to createairflow in a horizontal direction and the second blower is configured tocreate airflow in a vertical direction. Alternatively, single blower maybe configured to provide airflow in both a vertical and horizontaldirection by providing two separate air ducts from the blower to each ofthe air inlets 44 a and 44 b. Where separate first and second blowersare utilized, each blower may be configured to independently provide adifferent rate of airflow for the vertical and horizontal airflows. Forexample, one or more of the blowers may be configured to independentlyprovide sudden or increased airflow for the purpose of removing unpoppedkernels of popcorn from the heating chamber 18. Similarly, the verticaland horizontal airflows may independently provide hot air or cold air.

In some embodiments, the airflow is maintained at a velocity thatmaintains kernels in a generally circular flow pattern prior to popping,where the velocity is sufficient to selectively lift a popped kernel ofcorn out of the heating chamber 18 as a result of the increased dragcreated by the larger volume and irregular shape of the popcorn flake.In particular embodiments, the airflow has a flow-rate that will move avolume of kernels through a high intensity microwave region sufficientto rapidly and uniformly heat the load of unpopped kernels, whilemaintaining the unpopped kernels within the high intensity microwaveregion without being expelled.

In addition, in another embodiment, heated airflow may be used to removeresidual moisture from and brown popcorn flakes.

Preheating

In accordance with another aspect, the present invention provides a heatsource for preheating the one or more kernels prior to being disposedwithin the heating chamber. In some embodiments, the devices of theinvention may include a heater for heating the airflow to be passedthrough the heating chamber. The un-popped popcorn kernels may bepreheated by the heated airflow so as to increase the efficiency of thefinal microwave popping. Accordingly, in some embodiments, the systemsand devices may further comprise a heating element to cause heating ofthe airflow. In some embodiments, as shown in FIG. 1E, the air source orblower 40 a or 40 b may include heating elements 15 a and 15 b whichheat the airflow. The air being blown into the airflow chamber may, forexample, between ambient room temperature of about 20° C. to about 232°C., or alternatively from about 50° C. to about 150° C., oralternatively from about 70° C. to about 180° C., or alternatively fromabout 80° C. to about 95° C. Generally, popcorn pops when the popcornkernel reaches an internal temperature of approximately 135 psi (930kPa) and a temperature of about 180° C. (356° F.). Thus, the popcornkernels may be preheated, without resulting in popping, when heated to atemperature less than 180° C. (356° F.). In other embodiments, theheating chamber 18 within which the popcorn kernels are dispose mayitself be heated. In yet other embodiments, the popcorn kernels may bepreheated within the storage container used to dispense the popcornkernels into the heating chamber 18.

In other embodiments, the systems and devices of the invention may alsocomprise a heat source for preheating the one or more kernels prior tobeing disposed within the heating chamber. For example, the kernels maybe preheated with a heat source selected from one or more of a flame,infrared heat, convection heat or heat from a resistive element.

In some embodiments, the devices of the invention further comprise acontrol module for controlling the temperature, flow rate, and flow pathof the air.

Inlets/Outlets

As shown in FIGS. 1 and 1A, in some embodiments a popcorn kernel storagecontainer 66 is provided, which dispenses popcorn kernels through thedispensing tube 68 and into the heating chamber 18. An inlet 69 isconfigured to dispense a quantity of popcorn kernels into the heatingchamber 18. The inlet may be located either on the side wall 38, thebottom or the top of the heating chamber. FIGS. 1A and 1B show an inlet69 into the sidewall 38 of the heating chamber 18, allowing popcornkernels to be dispensed into the heating chamber by force of gravity.Popcorn kernels may be dispensed into the heating chamber from a storagechamber 66 that is connected to the heating chamber 18 by means of adispensing tube 68. The storage chamber 66 may be located above theheating chamber 18, where it can dispense popcorn kernels to the heatingchamber by gravity, or may alternative be located to the side of orbelow the heating chamber, where popcorn kernels would need to bedispense to the heating chamber by means of a conveyor, lift, plunger orairflow. In some embodiments, the inlet 69 is configured to dispensethrough popcorn kernels into the heating chamber 18 in such a mannerthat popcorn kernels circulating within the heating chamber 18 do notreenter the dispensing tube 68. For example, the inlet 69 may connect tothe heating chamber at an angle, such that popcorn kernels circulatingin one direction bypass the inlet 69 at an acute angle relative to theangle popcorn kernels enter the heating chamber 18 through the inlet 69and do not reenter the dispensing tube.

In some embodiments, the storage chamber 66 may also include a meteringdevice 67 for controlling the number of popcorn kernels being releasedinto the heating chamber 18 in batch mode. Alternatively, the meteringdevice 67 may control the rate of flow of popcorn kernels being releasedinto the heating chamber 18 for dispensing kernels in a continuous mode.For example, the metering device 67 may regulate the rate of flow toenable continuous feeding kernels into the heating chamber 18. Such ametering device includes, for example, a microphone for detecting thesound of a kernel popping, coupled to a controller that regulates one ormore process parameter, including air velocity, speed of circulatingkernels, input of new kernels, microwave intensity, etc.

The devices of the invention further include an outlet 34 from theheating chamber. In some embodiments, the devices comprise an outlettube 602 connected to the outlet 34 of the heating chamber 18. In someembodiments, the inner surface of the outlet 34 may comprise surfaceirregularities that assist in moving popped flakes to exit the outlet34. For example, in some embodiments, the inner surface may compriseirregular bumps or indentations. In other embodiments, the outlet tube72 may include a ribbed inner surface 73. By way of example, the ribbing73 on the inner surface 602 a of the outlet tube 602 may comprise ahelical coil or a plurality of individual rings fixed to the innersurface. Alternatively, the ribbing may comprise grooves machined intothe inner surface.

The microwave devices of the present invention may also include any oneof numerous sensory inputs that regulate the flow of popcorn kernelsinto the heating chamber, the rate of airflow, the degree of preheating,etc. For example, the present invention contemplates the use of amicrophone pop detector for sensing the sound created by the poppingkernel and/or the frequency of the noise of popping, coupled with thekernel flow metering unit that dispenses additional quantities ofpopcorn when the popping ceases or the frequency of popping falls belowa selected threshold. In addition, such inputs may include suddenincreased airflow to clean passageways of un-popped kernels or poppedflakes that may occasionally adhere to surfaces.

The use of high field intensity high intensity microwave regions forpopping popcorn kernels further enables novel kernel feed approaches.For example, in some embodiments, kernels may be sprayed onto a strip ofpaper having an edible adhesive surface and the strip of paper withadhere kernels may then be fed through the high intensity microwaveregion where the kernels pop and release from the paper, oralternatively pop and remain adhered to the paper.

Vending Machines

The systems, devices and methods of the present invention may also beutilized to provide popcorn vending machines, for rapid, automated andconvenient dispensing of popcorn at entertainment venues. For example,such automated vending machines may be configured to dispense aspecified quantity of popcorn to a purchaser upon activation of apurchase transaction via a customer interface 82 (as shown in FIG. 7)which is used to initiate the transaction by a purchaser. The purchasetransaction may comprise payment by coin, paper bill, a debit card orcredit card, pre-paid credit/debit card or gift card, internet bankingservice, token, near-field transmission card (radio frequencyidentification, or RFID), QR code, or the like. Thus, the device mayinclude any suitable customer interface capable of interacting with suchpayment methods. Such customer interface may include, for example, amagnetic card reader, a near-field reader, a QR reader, or a keypad tomanually enter credit card information. The purchase transaction maycomprise electronic payment activated by a mobile device. Any suitablemethod for initiating such a purchase transactions is contemplatedherein. The machines may, for example, be connected to the internet,either by wireless or telephone cable signal, with encryptedtransactions being activated by the purchaser on demand, and dispensingof product upon receipt of payment.

The vending machines contemplated by the present invention will behighly efficient in dispensing popcorn to purchasers as a result of therapid popping and the unique physical properties of the resultingpopcorn. The relatively small size of the devices disclosed herein areparticularly suitable for vending machines, which may be moved from onevenue to another, thus avoiding the need for dedicated machines thatremain at a venue permanently, even when no activities at the venue aretaking place.

The significantly increased popping rates achieved through the devicesand methods of the present invention further expand the utility ofpopcorn popping machines in commercial, military and humanitarianapplications. For example, the high intensity microwave region poppingmachines can produce significantly larger quantities of popcorn ondemand, within less than 20-30 seconds, such that it can keep up withcustomer demand at large entertainment venues, thereby increasing totalsales. Moreover, the relatively small size of the high intensitymicrowave region popcorn popping machines makes the machinessignificantly more portable, such that a single machine can be movedfrom one venue to another venue, thereby achieving a higher utilizationof a given machine.

The microwave popping machines disclosed herein may be operated from anysuitable power source, include a standard electrical outlet. Portablemachines may be powered either by standard electrical outlets availableat the venue source, or may be operated by generator, battery, solarpower, automotive power, or other available power supply. Battery orsolar powered devices may be useful, for example, when the device isused in remote locations where standard electrical power source isunavailable. It is understood by those skilled in the art that batteryor solar powered devices may require modifications to the electronicssystem that regulates operation of the device.

The vending machines disclosed herein may also comprise a high capacitystorage chamber 66, as shown in FIG. 7, suitable for storing sufficientquantities of kernels to be dispensed during high demand or for largegroups of individuals. Vending machines may also include, for example,metering devices 67 for controlling the quantity of kernels dispensedinto the heating chamber.

Methods

The improved system and method of making popcorn heats popcorn kernelswith microwave electromagnetic radiation by creating high intensitymicrowave regions within a heating chamber. The popcorn kernels areheated in the high intensity microwave regions until they pop intoflakes. During the process, airflow passes through the heating chamberfrom a lower portion of the chamber to an upper portion of the chamber.The airflow blows the popped popcorn out of the heating chamber as aresult of the increased drag coefficient of the larger irregularlyshaped popped popcorn, while allowing the smaller more uniformly shapedun-popped kernels to remain in the chamber until they eventually pop.

In one aspect, the present invention also contemplates novel methods formaking popcorn. In one embodiment, a method is provided that comprisesthe steps of passing electromagnetic microwave radiation through aheating chamber and maintaining at least one antinode of at least onemicrowave at a substantially fixed location within the heating chamber.The popcorn kernels are heated with the microwave radiation atapproximately the location of the one or more antinode.

In another aspect, the present invention provides a method of poppingpopcorn kernels, comprising moving popcorn kernels within a heatingchamber with airflow; and subjecting the popcorn kernels to microwaveenergy sufficient to cause the popcorn kernels to pop, resulting inpopped popcorn. In one embodiment, the microwave energy is focusedmicrowave energy.

In yet another aspect, the present invention provides a method forpopping popcorn kernels, comprising generating in a single-mode resonantmicrowave applicator a standing microwave energy field comprising anarray of one or more anti-node high intensity microwave regions, andsubjecting popcorn kernels to the microwave energy in the one or morehigh intensity microwave regions, sufficient for the popcorn kernels toachieve a uniform distribution of microwave energy heat to cause thepopcorn kernels to pop.

In yet another aspect, the present invention provides a method formaking popcorn, comprising generating in a single-mode resonantmicrowave applicator a standing microwave energy field comprising anarray of one or more high intensity microwave regions; providing aheating chamber encompassing the one or more high intensity microwaveregions; delivering popcorn kernels to the heating chamber, wherein thepopcorn kernels are moved through the microwave high intensity microwaveregion within the heating chamber to achieve a highly uniformdistribution of microwave energy heat until popped; and selectivelydischarging popped popcorn from the heating chamber by upward airflow.

Density

The methods and devices of the present invention were surprisinglyeffective in rapid and highly complete popping of popcorn kernels.Indeed, it was discovered that the above methods and devices producedpopcorn produced popcorn having unique and unexpected physicalproperties. While it has previously been believed that popping popcorntoo quickly is disadvantageous because the starch does not have time togelatinize, the popcorn popped in accordance with the principles of thepresent invention achieved surprising results which appear to showincreased expansion of the starch, resulting in a larger popcorn flake,as well as more complete popping of the popcorn kernel (with lessresidual unpopped popcorn shell), without undesirable burning of popcornflakes.

Yet another surprising result was the discovery that popcorn producedusing the methods and devices of the present invention resulted inpopcorn that was more completely popped, such that the resulting popcorncontained less residual un-popped kernel shell. Thus, the methods anddevices of the present invention improved popping efficiency (i.e., thecompleteness of popping of individual kernels), as measured by removingresidual un-popped kernel shells from the popped popcorn and determiningthe weight percent of the residual shells relative to the entire poppedkernel (popped portion, plus residual un-popped portion).

Among the many advantages of the popcorn flakes of the present inventionis that lower density popcorn flakes fill a larger volume of space,thereby reducing the amount (and cost) of popcorn kernels needed to filla specified volume purchased by a consumer and also reducing the numberof calories consumed by that consumer. Furthermore, the larger size ofpopped flakes further increases the surface area onto which coatings maybe applied, such as flavorings, colorings, etc.

Turning now specifically to the drawings, FIG. 1 shows a popcorn poppingsystem 10. In order to pop popcorn, kernels are dispensed into a heatingchamber 18. This may be done from a storage container 66 through adispensing tube 68 and through an inlet 69. The popcorn kernels aresubjected to microwave energy emitted from an antenna 24 connected to amagnetron 22. The microwave energy is contained in a waveguide 28 toestablish a substantially standing wave so that the microwave energy hasnodes of minimal energy and anti-nodes of maximal energy. The heatingchamber 18 is disposed about the anti-node so that the popcorn kernelsdisposed therein are exposed to high levels of focused microwave energy.

The focused microwave energy could quickly heat one side of the popcornand cause it to rupture. As noted above, very rapid heating haspreviously been taught to be disadvantageous, as the starch in thepopcorn kernels does not have time to gelatinize. In accordance with oneaspect of the present invention, however, it has been found that rapidheating of the kernel can actually provide improvements. By circulatingthe popcorn kernels in the heating chamber 18, the kernels revolvethrough the area within and around an anti-node, and may be heated moreuniformly within the individual kernels and as a group. This, in turn,allows the popcorn kernels to rupture in multiple locations atsubstantially the same time rather than rupturing at a single hot spot.Rather than having reduced gelatinization of the starch, the presentprocess appears to provide increased gelatinization and a popcorn flakeswhich are not only larger in volume than a conventional popcorn flake,but also at least as long, and frequently significantly longer, than aconventional popcorn flake.

The movement of the popcorn kernels in the heating chamber 18 can beaccomplished by a variety of methods. These may include forced aircirculation, rotating the heating chamber itself or other mechanismwhich may be apparent in light of the present disclosure. As shown inFIGS. 1 and 1A, the movement of the popcorn kernels may be accomplishedby an air source 40 such as a single air blower or a plurality of airblowers which inject air into the heating chamber generally parallel tothe bottom of the heating chamber 18. The airflow will initially followa generally circular path around the lower portion 30 of the heatingchamber 18 (as shown in FIG. 1A) and will then gradually move up throughthe heating chamber 18 in a helical path and out through the outlet tube60. Such a pattern not only moves the un-popped kernel in a generallycircular pattern, but it also lifts popped kernels out of the heatingchamber and into the outlet tube 60 and eventually into a receptacle 64.

While a single air source 40 may be used, two or more air sources may beused. For example, as shown in FIG. 1, one air source forces air throughan inlet 44 which is tangential to the cylindrical cross-section of thebottom of the heating chamber 18, while the other forces air through aninlet 44 b in the bottom of the heating chamber. Such a configurationallows for one air path to principally drive the corn kernels in acircular pattern within the heating chamber while the other air path isgenerally vertical and lifts popped flakes out of the heating chamberthrough the outlet 34. It will be appreciated that a single blower couldbe used to create both airflows, via a split air tunnel or tubing.

Heating elements 15 may be disposed along either air source 40 topreheat the air. It has been found that preheating the air can improvekernel rupture and reduces the amount of hull which is left over. Theheating elements 15 are advantageous as they provide additional controlover the heating gradient occurring with the popcorn kernels. Themicrowave energy heats the water contained in the kernels to gelatinizethe starch, while the heated air can be used to facilitate rupturewithin a desired window of time.

The airflow can also be used to regulate humidity. For example, ahumidifier 42 may be placed in communication with the blower 40. Thehumidifier can be used to add moisture to the air to get popcorn flakeshaving a desired consistency for adhering popcorn flakes together toform shapes, and also to improve the ability of popcorn flakes toreceive and retain flavorings such as salt and butter.

One interesting aspect of utilizing the method of the present inventionis that popcorn flakes made according to the present invention typicallyhave less hull remnants attached to each popcorn flake. Moreover, thehull remnants that do remain are generally lighter and softer than hullremnants which are part of conventional popcorn flakes.

Turning now to FIG. 2, there is shown an overlay of a heating chamber 18and a wave representing focused microwave energy 80 as may be achievedfrom a wave guide. The microwave energy 80 has nodes 82 of minimalenergy and anti-nodes 84 of maximal energy. At a frequency of 2.45 GHz,the wavelength is approximately 12.2 cm. Thus, the nodes 82 are spacedapart approximately 6.1 cm. Likewise, the anti-nodes 48 are spaced aparta similar distance. In order to contain the un-popped kernels 90 in thearea of the anti-node 84 and subject them to maximal energy, the popcornkernels are preferably contained in the half of the area most closelysurrounding the anti-node. Thus, the heating chamber 18 may be less thanone-half of the wavelength of the microwave energy, or alternativelyabout one-quarter of the wavelength, such as between about 2.5 and 3.1cm (1 and 1.25 inches) for 2.45 GHz.

As the kernels revolve and pass through the anti-node 84, the kernelsmore evenly heat. When the hull ruptures, the kernels expand outwardly.One surprising result of the present invention is that the flakes arelonger and may be larger than conventional flakes. It is believed thatthe increased size may be due to a more complete gelatinization of thestarch caused by the starch being more evenly heated.

Turning now to FIG. 3, there is shown an overlay between an alternateconfiguration of the heating chamber 18 a and the microwave energy 80.Rather than using a heating chamber which is about one-quarter ofwavelength in diameter, the heating chamber is about one-half thewavelength (i.e. between about 5.9 cm and 6.5 cm (2.25-2.5 inches) indiameter). This places the popcorn kernels 90 in a position where theyrepeatedly pass through the anti-nodes 84 of the microwave energy 80.While such a configuration is advantageous over the art, it is believedthat the configuration shown in FIG. 2 is more advantageous.

While the use of airflow is advantageous to move the popcorn kernels inthe heating chamber 18, it is not necessary. For example, FIG. 4 shows aheating chamber 18 b in the form of a spinning cup. The spinning cup 18b supplies centrifugal force to the kernels, thereby keeping the kernelsmoving around and through the anti-node 84 or plane of maximal energy ofthe microwave energy.

To prevent the un-popped kernels 90 from escaping from the spinning cup18 b, an annular lip 50 or a series of projections may be disposedadjacent the top of the spinning cup. The lip 50 is preferably sized tocontain un-popped kernels, while allowing popcorn flakes to easily passout of the heating chamber 18 b. Thus, for example, the lip 50 mayextend between about 1-10 mm. Unpopped kernels will run into and be heldin the heating chamber 18 b by the lip, but the larger popcorn flakes 94will easily pass the lip and leave through the outlet of the heatingchamber.

While discussed as being moved by airflow and a spinning cup, it will beappreciated that other means exist for spinning the popcorn within theheating chamber so as to circulate the kernels about the anti-node 84.Such other means are intended to be covered by the appended claims.

FIG. 5 shows an overlay of a microwave energy pattern 80 and a pluralityof heating chambers 18 of the present invention. While a portion of onewavelength of the microwave energy may be used, the waveguide or otherstructure may be used so that multiple wavelengths are used to therebyallow multiple heating chambers to be used. Such a configuration may bebeneficial, for example, in commercial applications where large volumesof popcorn are desired.

FIG. 1A shows a view of a heating chamber outlet tube 60 comprising aninterior 72 a having ribbing 73. In accordance with one aspect of thepresent invention, it has been found that the use of ribbing 73 alongthe inner surface 72 a of the outlet tube 60, or a helical wire in theoutlet tube, enhances popcorn flow through the outlet tube.

While rapid heating has previously been thought to inhibitgelatinization and expansion of the starch, it has been found inaccordance with the principles of the present invention that the averagepopcorn kernel is at least as large as that cooked in accordance withprior art methods. Moreover, testing (as described in the Examples,below) has demonstrated that the popcorn formed in accordance with thepresent invention is longer than conventional popcorn flakes, therebyproviding increased volume per kernel. This enables a given volume ofpopcorn to be sold having fewer calories.

While FIG. 1 shows one embodiment of a microwave wave guide which can beused in accordance with the principles of the present invention, it willbe appreciated that other types of wave guides may be used. For example,FIG. 6 shows an alternative microwave waveguide applicator 100 forpopping popcorn kernels. The applicator 100 includes a magnetron 102, anantenna 104, a wave guide 106 which is generally circular and a heatingchamber 108 in which the popcorn kernels may be disposed.

As shown in FIG. 7, the devices of the present invention may also beconfigured with a portable power supply 81, such as a battery, solarpower generator, or hookup for an automobile battery. The portabledevice may include, for example, a customer interface 81 operablyconnected to the electronics system 81 that communicates with a paymentsource where funds are located for payment of the product resulting fromthe device.

The popped flakes produced using the devices and methods disclosedherein may be used in numerous applications, including food products,packaging materials (i.e., for thermal insulation, cushioning of fragilematerials, etc.), confetti for celebratory or entertainment events, andthe like.

Thus, there are disclosed new apparatuses and methods for poppingpopcorn. It will be appreciated that numerous modifications may be madewithout departing from the scope and spirit of the invention. Forexample, the present invention may be modified further by addingmultiple output ports to increase the volume of popcorn flakes produced,or may be modified with air blowers at or near the exit tubes so as toincrease the velocity of popcorn flakes exiting the device, or may bemodified by adding other obvious features, such as handles, wheels,packing cases, etc. The appended claims cover such modifications to thedevices and methods claimed below.

Examples Comparison of Popped Flakes Using Focused Microwaves

The following tests were conducted to compare popcorn flakes made usingthe focused microwave system of the present invention with popcornflakes made using standard hot air popper method and a standard kitchenmicrowave device.

Devices Used.

The standard kitchen microwave device used in these experiments (to popthe microwave bag popcorn) was an Amana Radarrange brand microwavesystem, Model MVH250W, configured for an output of 1.0 kW (with an inputof 1.5 kW) at a frequency of 2.54 GHz. The microwave popcorn used wasPop-Secret Premium Popcorn Sea Salt (3.5 oz bag).

The hot air popper used in these experiments was a West Bend Hot AirPopper, operated at 1.2 kW of power.

The focused microwave applicator system used in these experiments was apilot-scale microwave food processing unit that utilized a rectangularsingle-mode microwave resonant cavity having a cross section of 8.6cm×4.3 cm (3.4″×1.7″) and a length of 12.7 cm (5″). The focusedmicrowave applicator was operated at 1.1 kW of power and appliedmicrowaves at a frequency of 2.54 GHz. The focused microwave applicatorwas also configured with a hot air blower for circulating popcornkernels and preheating the popcorn kernels with hot air at a temperatureof 81° C.

Methods.

Volume capacity means the volume of 60 popped popcorn flakes. Volumecapacity is determined by randomly selecting 60 popcorn flakes popped bya particular popping method or system, placing the 60 popcorn flakes ina graduated cylinder, followed by 6 gentle shakes (of approximately ½inch length motions on a soft surface, by tapping the top of thecylinder with a hand), and repeating until the volume measurement doesnot change by any statistically significant margin. Average volumecapacity is determined by taking the above measurements of at least 8batches of 60 popcorn flakes.

A 1000 mL 2.5 in diameter glass graduated cylinder was used to measurethe volume of 60 popped flakes to determine the density of the flakes.After the popcorn was popped, popped flakes were put in a cylinder andthe volume of the popped flakes was measured as follows. The cylinderwas shaken 6 times (approximate ½ inch length motions accomplished bysetting the cylinder on a compliant surface such as a chair cushion andthen hitting the top of the cylinder with ones hand), a measurement wasretaken, and the shaking procedure was repeated until the volume did notchange. The final stable volume measurement was the measurement used.All measurements were taken on the day that the flakes were popped, toavoid possible changes to volume occurring over time (due to breakage offlakes or due to the flakes drying out).

The tests were conducted by popping popcorn kernels obtained from thesame source of kernels, but using the following three different methodsof popping: (1) focused microwaves in accordance with a device of thepresent invention (8 Batches, 480 kernels, 469 popped), (2) a hot airpopping machine (9 Batches, 540 kernels, 483 popped), and (3) acommercially available microwave bag in a standard kitchen microwave (4Batches, 1369 kernels, 1275 popped).

Results.

The results showed that focused microwave popped flakes not only hadsignificantly improved volume, but also that the focused microwavedevice was significantly more efficient, resulting in a significantincrease in the percentage of popcorn kernels popped in each batch(popping yield). The hot air popped popcorn proved to have the lowestvolume. Therefore it was used as the base volume and the percentageincrease was calculated using the following formula: (Vol A−Vol AirPopped)/Vol Air Popped. Thus the percent increase volume of Hot AirPopped versus Hot Air Popped equals zero. The percentage of kernelspopped was determined by placing 60 Kernels in the focused microwavepopper as well as the hot air popper. In the microwave bag test themicrowave bag was popped first then the kernels counted afterwards. Thenthe percentage popped is calculated. Time to first pop was determined byplacing kernels in their popping machine and starting the timer themoment the machine is turned on. When the first pop was heard the timewas recorded. Finally, the time to last pop was determined by placingthe kernels in their popping machine and starting the timer the momentthe machine is turned on. As the popping rate slowed down, the usernoted the time of each of the last pops. Once the popping has ended, themachine was turned off and the last of the last pop times was used tomark the last pop. The results obtained are shown below in Table A.

TABLE A Comparison of Focus Microwave Popcorn Flakes with Hot Air andMicrowave Bag Flakes Average Average time Average % Increase time tolast Method Volume in Volume % Popped to first pop pop Focused 542 mL30% 98 10 17 Microwave Microwave 480 mL 15% 93 69 189 Bag Hot Air 418 mL0% 89 48 78 Popped

Table A shows that the device and methods of the invention significantlyimprove the average volume of popcorn flakes compared to using a hot airpopper or a microwave bag. While hot air popping and microwave bagpopping resulted in an average volume of popped flakes of 418 mL and 480mL, respectively, the use of focused microwave device of the presentinvention resulted in an average volume of 542 mL, which represents a13% improvement over the microwave bag method and a 30% improvement overthe hot air method. Specifically, the device and methods of the presentinvention were successful in improving the average volume of poppedflakes to greater than 480 mL.

Table A further shows that the device and methods of the inventionsignificantly improve the efficiency of popping kernels compared tousing a hot air popper or a microwave bag. While hot air popping andmicrowave bag popping resulted in an average popping efficiency of 89%and 93%, respectively, the use of focused microwave device of thepresent invention resulted in an average popping efficiency of 98%

Table A also shows that the device and methods of the inventionsignificantly improve the speed of popping, including the speed at whichthe first kernel is popped and the speed at which the last kernel ispopped. While hot air popping and microwave bag popping resulted in anaverage first pop time of 48 seconds and 69 seconds, respectively, theuse of focused microwave device of the present invention resulted in anaverage first pop time of 10 seconds. Moreover, while hot air poppingand microwave bag popping resulted in an average last pop time of 78seconds and 189 seconds, respectively, the use of focused microwavedevice of the present invention resulted in an average last pop time of17 seconds.

1. An apparatus for popping kernels, comprising: a heating chamberconfigured to contain kernels; a single mode resonant microwaveapplicator including a wave guide and a microwave emitter configured toproduce microwave energy within the heating chamber and heat the kernelsthe wave guide and the microwave emitter cooperating to generate astable focused high intensity microwave region within the heatingchamber, the heating chamber being disposed within the wave guide; andan air blower configured to create airflow within the heating chambersufficient to move the kernels within the heating chamber.
 2. Theapparatus of claim 1, wherein the air blower is configured to movekernels in the heating chamber at a sufficient speed to substantiallyuniformly heat the kernels.
 3. The apparatus of claim 1, wherein the airblower is configured to cause airflow within the heating chamber in ahorizontal direction sufficient to move kernels in a generallyhorizontal and generally circular path in the heating chamber. 4.-9.(canceled)
 10. The apparatus of claim 1, further comprising a heatingelement disposed in communication with the air blower to cause heatingof the airflow.
 11. The apparatus of claim 1, wherein the high intensitymicrowave region includes a microwave energy maxima located within theheating chamber. 12.-13. (canceled)
 14. The apparatus of claim 13,wherein a plurality of high intensity microwave regions are locatedwithin the heating chamber.
 15. The apparatus of claim 1, wherein thehigh intensity microwave region includes a microwave energy maximalocated within the heating chamber.
 16. The apparatus of claim 15,wherein a single high intensity microwave region is located within theheating chamber.
 17. The apparatus of claim 15, wherein a plurality ofhigh intensity microwave regions are located within the heating chamber.18. The apparatus of claim 1, wherein the diameter of the heatingchamber is such that kernels circulating within the heating chamber passthrough a microwave energy maxima of two adjacent high intensitymicrowave regions.
 19. The apparatus of claim 1, wherein the heatingchamber encompasses a perimeter of two adjacent high intensity microwaveregions that excludes a microwave energy maxima.
 20. The apparatus ofclaim 1, wherein the heating chamber has a diameter which is less thanthe microwave wavelength.
 21. The apparatus of claim 15, wherein theheating chamber has a diameter which is less than one-half the microwavewavelength.
 22. The apparatus of claim 1, wherein the heating chamberdiameter is between about 4.45 cm and 7.62 cm.
 23. The apparatus ofclaim 22, wherein the heating chamber diameter is between about 5.08 cmand 6.35 cm.
 24. The apparatus of claim 1, wherein the single-moderesonant microwave applicator generates a standing microwave patterncomprising an electric field distribution of n half-wavelengths, where nis an integer.
 25. The apparatus of claim 15, where n is greater than 1.26. The apparatus of claim 1, wherein the device is configured such thatthe heating chamber is between two adjacent microwave energy minimanodes.
 27. The apparatus of claim 1, comprising a plurality of anti-nodehigh intensity microwave regions.
 28. The apparatus of claim 26, whereinthe heating chamber encompasses a plurality of high intensity microwaveregions and wherein the blower is configured to rapidly move the kernelsthrough the high intensity microwave regions.
 29. The apparatus of claim1, comprising a plurality of heating chambers, wherein substantially allof each of the one or more high intensity microwave regions is locatedwithin one of the plurality of heating chambers.
 30. The apparatus ofclaim 1, wherein single-mode resonant microwave applicator is configuredto generate microwave intensity within the heating chamber to subjectthe kernels to microwave energy sufficient to pop one or more of thekernels within approximately 10 seconds.
 31. An apparatus for poppingkernels, comprising: a heating chamber configured to contain kernels; amicrowave emitter configured to produce microwave energy within theheating chamber and heat the kernels; a single-mode resonant microwaveapplicator configured to generate a stable focused high intensitymicrowave region within the heating chamber; and an air blowerconfigured to create airflow within the heating chamber sufficient tomove the kernels within the heating chamber.